Kinanthropometric profile, hip bone mineral density, and the incidence of bone stress fractures in professional middle and long-distance runners

Purpose: This study aimed to identify the kinanthropometric profile, hip bone mineral density (BMD), and frequency of bone stress fracture (BSF) in professional middle-distance and long-distance runners. Methods: Thirty-seven professional male runners participated: middle-distance runners and long-distance runners aged 23.6 ± 2.6 years with over 6 years of training experience. Kinanthropometric measurements were performed according to ISAK standards, including body composition and Heath-Carter somatotype assessment (endomorphy, mesomorphy, ectomorphy). Hip BMD, bone mineral content (BMC), and T-scores were measured using DXA at the total and femoral neck (FN) and trochanter (TR) regions. BSF history was collected through face-to-face interviews and medical records. Body Mass Index (BMI) was calculated. Results: Middle-distance runners presented superior all bone parameters (large effect: > .8). Long-distance runners have the highest frequency of fracture incidence compared to middle-distance runners (68.5% vs 66.5%). The results of covariance analyses showed that BMD FN was significantly influenced by muscle mass (kg) and endomorphy (scores) (adj. R2 = .56). The same effect of these two variables was noted on the T-score FN (adj. R2 = .75). In turn, BMC FN was affected by the type of sports competition, muscle mass (kg), and endomorphy (scores) (adj. R2 = .84). BMD TR was significantly influenced by: endomorphy (scores) and mesomorphy (scores) (adj. R2 = .78). BMC TR was significantly affected by muscle mass (kg) (adj. R2 = .75). In turn, T-score TR was influenced by muscle mass (kg), endomorphy (scores), and mesomorphy (scores) (adj. R2= .68). Conclusions: This study demonstrated that the type of athletic training and body tissue composition had a significant impact on BMD in the hip region. The type and specificity of training in middle-distance runners had a more favourable effect on bone parameters compared to long-distance runners. This relationship may be related to the greater mechanical load resulting from greater muscle mass and more intense osteogenic stimuli.